This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
Various methods have been developed for determining the location of the mobile terminal. For example, some mobile terminals may include GPS as part of the device. GPS systems/services utilize satellites to triangulate to the location of a GPS-enabled device. Alternatively, other methods utilize a ground based network of antennas or base stations to determine the mobile terminal location. For example, an application program might make a request to a wireless carrier network. The wireless carrier would then use one of several methods to determine a user's location on the wireless network and return the latitude and longitude coordinates to the application program. One method involves identifying the cell or base station closest to the mobile terminal. The antenna in communications with the mobile terminal may then be used to determine the relative direction of the mobile terminal. Using the round trip time, the distance from the base station can be determined providing an location with an accuracy approaching 100 meters. Another method using multiple base stations may be used in some circumstances. The location of the mobile terminal can be determined using typically three base stations capable of communicating with the mobile terminal and triangulating the estimated location of the mobile terminal from each individual base station. More precise location estimates approaching 30 meters can be achieved using this method.
It is currently not possible for an electronic device, such as a mobile device, to position itself and to navigate within large buildings, e.g., malls, large office buildings, public buildings (museums, city halls, conference centers, etc.), covered parking lots, etc. Structures and buildings such as these can be up to 1 mile long, for example, with multiple entrances, multiple floors, multiple sections, wings, and in the case of malls, an abundance of shops.
Certain location and navigation systems utilize signals from at least one WLAN AP when such signals are available. For example, Skyhook (skyhookwireless.com) uses a technology for outdoor positioning and navigation (based on WLAN AP locations). However, such technology operates by mapping a WLAN AP beacon (that is found by driving around and scanning) to geolocation coordinates, where the signal was detected, thus still necessitating GPS signal availability. U.S. Pat. No. 7,228,136 and U.S. Patent Publication No. 2007/0149215 describe using WLAN for location using triangulation of signals on multi channel mobile devices, while U.S. Pat. No. 6,807,478 described in-building navigation using light sources. Additionally, a report entitled “The Integration of Positioning Technologies for Precise Location Identification” by T. Y. Chew, available at http://ro.uow.edu.au/thesesinfo/5/, describes the integration of multiple positioning technologies, e.g., combining GPS and Third Generation (3G) networks.